Falling apart..advice

Been with my fiancé for 9 years both 24 now & I knew him since I was 5 years old we grew up as best friends and I’m sad to even start feeling like this .... we were ready to start taking that step forward to start planning our wedding now that we can afford it.....but lately I’ve been feeling unsure..I love him and our kids (5 yr old & 2 month old) I feel like I’m not 100% happy and confident that we will have a happy marriage. Our communication has got a bit worse I don’t feel like I can trust him when it comes to small things and that’s where our arguments begin. Like right now earlier after work he said he was going to hangout with the guys for a little bit and he’s still not home! I know he’s a grown man and I’m not his mother but come on you have a family at home? when we fights it’s mostly because of him I feel like I can’t do this I’m sick of it but I can’t see my life without him or our family splitting..idk how to go through this or what to think .. it’s just the same crap over and over.. don’t get me wrong he’s a really good guy and does a lot for us but I think our relationship should be way better than this. I don’t have really anyone to talk to but anything..advise..your stories..would be appreciated